A great variety of internestable interlockable seams have been proposed including, in particular, seams extruded from elastomeric material and formed with cooperating interlockable grooves. Some of these can be closed by the application of finger pressure when the parts are placed in juxtaposition whereas the closure of others is greatly expedited by an appropriately designed closure device as it is advanced along the seam members. Various designs for such devices each specially designed for use with a particular seam construction are disclosed in the following U.S. Pat. Nos., namely Sander 2,764,793 and 2,810,944; Berry 3,153,269; Plummer 3,234,614, 3,404,437, 3,478,404; and Bannies 3,572,191, 3,808,665. These several constructions have been commercialized and have served their intended purposes of closing a continuous separable seam of the particular type for which each of these devices was designed. However, no one of these prior constructions is useful in closing a snaplock seam having laterally facing internestable interlockable V-shaped portions extending therealong.